Film forming apparatus and film forming method

ABSTRACT

A film forming apparatus comprising a substrate holding section for holding a substrate to be processed, a nozzle unit arranged and opposing the substrate holding section, having a discharge hole for continuously applying film-forming solution, in the form of a slender stream, to a surface of a substrate held by the substrate holding section, and a drive mechanism for driving the substrate and the nozzle unit relative to each other, thereby to coat the surface of the substrate with the solution, while the nozzle unit is applying the solution, in the form of a slender stream, to the surface of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional under 37 C.F.R. 1.53 (b) of pendingU.S. patent application Ser. No. 09/328,771, filed Jun. 9, 1999 now U.S.Pat. No. 6,416,583, which is based upon and claims benefit of priorityof Japanese Patent Application No. 10-173229, filed Jun. 19, 1998, andJapanese Patent Application No. 10-364943, filed Dec. 22, 1998, wherebythe entire contents of the three patent applications are beingincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a film forming apparatus which appliesa solution having resin or the like dissolved in it, particularly aresist solution, onto a substrate to be processed, such as asemiconductor wafer, an LC substrate, an exposure mask, or the like.

In the process of manufacturing an LCD or a semiconductor device, forexample, photolithography technique is employed to form minute circuitpatterns.

In the photolithography technique, resist solution is applied to thesurface of a substrate to be processed, such as an LCD substrate, asemiconductor wafer, or the like, thereby forming a film thereon.Thereafter, the film is light-exposed to a specific pattern. Further,the film is subjected to developing and etching, to have a specificcircuit pattern.

At present, the spin coating method is most popular as a method ofapplying resist solution to a substrate to be process and forming a filmthereon. In the spin coating method, the resist solution is dripped ontothe center part of the substrate, and the substrate is rotated at highspeed. The resist solution is thereby spread over the entire surface ofthe substrate by virtue of centrifugal force. As a result, a resistsolution film, which is substantially uniform, can be is formed all overthe surface of the substrate.

In recent years, there is the trend that circuit patterns to be formedby photolithography technique have smaller and small wire width. It istherefore strongly demanded that the resist film be made thin. Namely,since the wire width of the circuit to be formed is proportional to thethickness of the resist film and the wavelength of exposure light, it isdesirable to make the resist film as thin as is possible.

With the spin coating method it is possible to reduce the thickness ofthe resist film, by increasing the rotation speed of the substrate.Thus, an 8-inch wafer, for example, is rotated at a considerably highspeed of 2000 to 4000 rpm.

The resist applying method, which uses the conventional spin coatingmethod, has the following problems that should be solved.

(1) In the spin coating method, if the substrate to be processed islarge, its the circumferential speed is high, causing a turbulent flowof air. The turbulent flow may vary the thickness of the resist film.Due to this, the exposure resolution will be decreased.

The decrease in exposure resolution is a fatal obstruction to anintended increase in the integration density of semiconductor devices.Inevitably, with the conventional spin coating method it is difficult toobtain a uniform resist film having a thickness of 0.4 μm or less.Hence, there is limitation to the manufacture of semiconductor devicesof about several gigabytes.

(2) In the spin coating method, the solvent contained in the resistsolution gradually evaporates as the resist solution spreads from thecenter part of the substrate toward the peripheral part thereof.Therefore, the viscosity of the resist solution changes in the directionthe solution spreads. Those parts of the resist film, which lie on thecenter and peripheral parts, respectively, may differ in terms ofthickness.

(3) In the spin coating method, the resist solution is wasted in a largeamount, spinning off from the peripheral part of the wafer, because thesubstrate to be processed is rotated at high speed. In one instance,only 10% or less of the resist solution applied onto the wafercontributes to the forming of a resist film.

(4) Further, in the spin coating method, the wafer must be rotated in acup in order to receive the resist solution spinning off. The resistsolution sticking to the cup form particles, which may contaminate thesubstrate being processed. Hence, it is necessary to wash the cupfrequently.

(5) Still further, the spin coating method is disadvantageous in thatthe resist solution may be applied also to that region of the substrate,such as the peripheral part, which does not contribute to the forming ofa circuit. The resist solution applied to this part is usually removedright after the step of applying the resist solution, by a dedicatedapparatus called “edge remover”.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in view of the facts mentioned inthe paragraphs (1) to (5). Its principal object is to provide a filmforming apparatus which can greatly save the solution used to form afilm and which can uniformly apply the solution to only the desired partof the substrate that is to processed.

According to the first aspect of this invention, there is provided afilm forming apparatus which comprises: a substrate holding section forholding a substrate to be processed; a nozzle unit arranged and opposingthe substrate holding section, having a discharge hole for continuouslyapplying film-forming solution, in the form of a slender stream, to asurface of a substrate held by the substrate holding section; and adrive mechanism for driving the substrate and the nozzle unit relativeto each other, thereby to coat the surface of the substrate with thesolution, while the nozzle unit is applying the solution, in the form ofa slender stream, to the surface of the substrate.

With this structure it is possible to apply solution, such as resistsolution, in a manner of so-called single-stroke writing. Therefore, theuse efficiency of resist solution for forming a film can be muchincreased. To form a thin film having a uniform thickness, it isnecessary to discharge the solution at high pressure in as slender astream as possible, while moving the nozzle unit at high speed. In thiscase, it is required that interruption of the solution stream beprevented effectively. To this end, it is desirable to provide anatmosphere control mechanism for maintaining a solvent atmosphere havinga predetermined concentration in a space into which the nozzle unitapplies the solution.

Here, the atmosphere control mechanism has a main body for accommodatingthe substrate to be process, a solvent channel provided in the main bodyfor storing solvent controlled in temperature and surface level, and atop plate member provided above the main body and partitioning the spaceinto which the nozzle unit applies the solution. In this case, the topplate member has an insertion section in which the nozzle unit isinserted.

Further, the top plate member may have heating means for heating thenozzle unit and the space into which the nozzle unit applies thesolution. If so, the solvent atmosphere can be controlled better, andthe viscosity of the solution can be controlled as is desired.

Preferably, the nozzle unit has a solution nozzle for applying thesolution in the form of a slender stream, and a solvent nozzle forpassing solvent around the solution applied from the solution nozzle.

In this case, the solvent is prevented from evaporating from thesolution immediately after the solution is discharged from the nozzleunit, thus effectively the viscosity of the solution from changing.Interruption of the slender stream of the solution can thereby beavoided.

A route-speed setting section may be provided to set a speed at whichthe nozzle unit and the substrate are moved relative to each other and aroute along which the solution is to be applied, in accordance with theamount of solution to apply, the time of applying the solution and thearea to coat with the solution. Then, a film of the solution, which isthin and has a uniform thickness, can be formed on the substrate.

Various types of solution application routes can be set. For example, azigzag route or a spiral route may be set.

To render the thickness of the solution film uniform, it is necessary tomaintain the relative speed between the substrate and the nozzle at aconstant value. To this end it is desired that a mask member be providedto cover the substrate, except a film-forming region thereof, and thatthe nozzle unit and the substrate be decelerated, returned andaccelerated over the mask member and moved at a constant relative speedover the film-forming region of the substrate.

The mask member may be a plate having an opening that corresponds to thefilm-forming region. Alternatively, the mask member has a pair ofsolution receiving members and a drive mechanism for driving thesolution-receiving members to control a distance between the solutionreceiving members.

Further, the solution may be one selected from the group consisting ofresist solution, solution for forming an interlayer insulating film,solution for forming a highly conductive film, ferroelectric solution,sliver paste and the like.

According to the second aspect of the present invention, there isprovided an apparatus for forming a film on a substrate to be processed,which comprises: a substrate holding section for holding the substrate,with the surface thereof turned downwards; a nozzle unit having adischarge hole for discharging the solution in a form of a slenderstream, the discharging hole turned upwards and opposing the substrateheld by the substrate holding section; and a drive mechanism for drivingthe substrate holding section and the nozzle unit relative to eachother, thereby to coat the surface of the substrate with the solution,while the nozzle unit is applying the solution, in the form of a slenderstream, to the surface of the substrate.

With this structure it is possible to apply solution, such as resistsolution, in a manner of so-called single-stroke writing. The useefficiency of resist solution for forming a film can therefore be muchincreased. Since the substrate is held with that surface turneddownwards and the solution is discharged upwards to coat the surface ofthe substrate, the substrate serves as a cover, effectively preventingsolvent from evaporating form the solution, such as resist solution. Asa result, Interruption of the slender stream of the solution can beavoided.

Moreover, with this structure, air can be easily expelled since thenozzle unit is arranged with its discharge hole turned upwards.

In the present invention, to form a thin film having a uniformthickness, the solution is discharged at high pressure in as slender astream as possible, while moving the nozzle unit at high speed. Thus, itis preferred that the discharge hole of the nozzle unit have a diameterof 10 to 200 μm.

It is desirable for this apparatus to further have a reversing mechanismfor turning the substrate upside down. The reversing mechanism needs tohold the substrate, without touching that surface of the substrate onwhich a film will be formed.

Such a slender nozzle as the one used in the present invention has theproblem that the discharge hole is easily clogged when it stopsdischarging resist solution. It is therefore desirable that the nozzleunit have a solvent supplying mechanism for discharge a solvent throughthe discharge hole of the nozzle unit.

According to the third aspect of the present invention, there isprovided a method of forming a film on a surface of a substrate,comprising the steps of: holding a substrate to be processed; anddriving the substrate and a nozzle unit relative to each other, whilecontinuously applying film-forming solution, in the form of a slenderstream, to the surface of a substrate, thereby to form a film on thesubstrate.

With this method it is possible to apply solution, such as resistsolution, in a manner of so-called single-stroke writing. The useefficiency of resist solution for forming a film can therefore be muchincreased.

It is desirable that this method have a step of covering the substrate,except the film-forming region, with a mask member.

Preferably, the method further comprises an agitation step of vibratingthe substrate coated with the solution, thereby to render flat a surfaceof a solution film formed on the substrate.

The method may comprise a step of holding the substrate, with thesurface, on which a film is to be formed, turned downwards, and thesubstrate and a nozzle unit may be driven relative to each other, whilecontinuously applying film-forming solution, in the form of a slenderstream, to a surface of a substrate, thereby to form a film on thesubstrate. In this case, the method needs to include a step of turningthe substrate upside down to hold the substrate with that surface turneddownwards.

It is desired that the method include a step of holding the nozzle unitat a wait position, before a film is formed on the substrate, and thatsolvent be passed through the discharge hole of the nozzle unit, therebyto prevent clogging in the discharge hole.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate preferred embodiments of theinvention, and together with the general description given above and thedetailed description of the preferred embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a vertical sectional view schematically showing a resistsolution applying apparatus according to this invention;

FIG. 2 is a plan view of the resist solution applying apparatus;

FIG. 3 is a perspective view for explaining the route along which theresist solution is applied;

FIG. 4 is a vertical view depicting the main part of a nozzle unit;

FIG. 5 is a plane view of the coating/developing system incorporatingthe resist solution applying apparatus according to this invention;

FIG. 6 is a side view of the coating/developing system;

FIG. 7 is a front view of the coating/developing system, for explainingthe function thereof;

FIG. 8 is a vertical sectional view showing another type of a nozzle foruse in the resist applying apparatus according to the invention;

FIG. 9 is a perspective view illustrating another route along which theresist solution is applied;

FIG. 10 is a plan view depicting still another route along which theresist solution is applied;

FIGS. 11A to 11D are perspective views of different mask members;

FIG. 12 is a perspective view for explaining the outline of the methodof forming a film by means of the resist solution applying apparatusaccording to one embodiment of the invention;

FIGS. 13A and 13B are partial sectional views showing the resistapplying apparatus;

FIG. 14 is a plan view illustrating the resist applying apparatus;

FIG. 15 is a schematic diagram showing a nozzle unit and a systemconfiguration;

FIG. 16 is a perspective view showing a reversing mechanism; and

FIG. 17 is a flow chart for explaining the process of forming a film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below, withreference to the accompanying drawings.

(First Embodiment)

First, the first embodiment of the invention will be described withreference to FIGS. 1 to 10 and FIGS. 11A to 11D.

The film forming apparatus according to this embodiment is, for example,a resist solution applying apparatus that applies resist solution(film-forming solution) to a semiconductor wafer (substrate to beprocessed).

The present invention is characterized in that the resist solution 3 isapplied to only the circuit-forming region la of the wafer, in a mannerof single-stroke writing, by moving a resist-solution applying nozzleunit 2 and the wafer 1 relative to each other as shown in FIG. 3.Namely, the resist solution is not applied to the wafer 1 while thewafer 1 is being rotated at high speed as in the conventional spincoating method.

In this embodiment, a mask member 4 is placed right above the wafer 1,covering the peripheral part of the wafer 1 and not covering thecircuit-forming region la. The nozzle unit 2 is reciprocated in Xdirection, while intermittently moved in Y direction at a predeterminedpitch. The resist solution is thereby applied to the circuit-formingregion 1 a only.

In this invention, various measures, which will be explained below, aretaken to apply resist solution in a single-stroke writing manner in theresist solution applying apparatus applied to the photolithographytechnique employed in the manufacture of a semiconductor device.

(Resist Solution Applying Apparatus)

FIG. 1 is a vertical sectional view schematically showing this resistsolution applying apparatus, and FIG. 2 is a plan view of the apparatus.

As shown in FIG. 1, the apparatus has a frame 5, a wafer holder 6(substrate holding section of the invention) for holding thesemiconductor wafer 1, a temperature-controlled top plate 7 secured tothe frame 5 and covering the wafer holder 6, and the solution applyingnozzle unit 2 extending through a slit 7 a (insertion passage of theinvention) made in the top plate 7, opposing the wafer W1 and driven inX direction with respect to the wafer 1.

The frame 5 is, for example, a channel-shaped member opening at the top,as is illustrated in FIG. 1. As shown in FIG. 2, the frame 5 iselongate, extending in the Y direction. Its one end, as viewed in the Ydirection, is a resist solution applying section R, and its other end isa wafer load/unload section L. A pair of Y rails 9 extend between theresist solution applying section R and the wafer load/unload section L,for holding the wafer holder 6 and allowing the same to move in the Ydirection.

Designated at numeral 10 in FIG. 2 is a ball screw mechanism for drivingthe wafer holder 6 in the Y direction to position the same with respectto the Y direction. The ball screw mechanism 10 has a ball screw 11rotatably supported by the walls 5 a and 5 b of the frame 5, which arespaced in the Y direction, and a Y drive motor 12 for rotating the ballscrew 11.

As shown in FIG. 1, the wafer holder 6 is held on the Y rails 9, by wayof a slider 13, to move in the Y direction. A nut 14 is secured to thelower surface of the wafer holder 6. The ball screw 11 is set in screwengagement with the nut 14. Thus, the wafer holder 6 can be freelypositioned in the Y direction when the Y drive motor 12 rotates the ballscrew 11, which is set in screw engagement with the nut 14.

The wafer holder 6 has a cup-shaped main body 16 and a wafer suctiontable 17 for holding the wafer 1. The main body 16 has a solutionchannel 18, which opposes the lower surface of the wafer 1 in order tostore solvent (thinner solution). The solution channel 18 is filled withthe solvent, which is controlled in temperature and surface level. Thesolvent evaporates, maintaining the wafer 1 in a solvent atmosphere thathas a predetermined concentration.

A solvent temperature control section 20 and a solvent supplying section21 are connected to the solvent channel 18, to supply the solvent andcontrol the temperature and surface level of the solvent. The solventtemperature control section 20 may be one that suppliestemperature-controlled solvent into the solution channel 18.Alternatively, the section 20 may be one that controls a heater (heatingmeans of the invention) provided in the main body 16 to directly controlthe temperature of the solvent filled in the solvent channel 18.

The solvent supplying section 21 has means for monitoring the surfacelevel of the solvent in the solvent channel 18, such as a pressure tube.Thus, the section 21 has the function of supplying the solvent, whilemonitoring the surface level of the solvent. The solvent may be suppliedin either replenishment scheme or circulation scheme. In thereplenishment scheme, the solvent is replenished for only the amountevaporated from the solvent channel 18. In the circulation scheme, thesolvent is circulated in the loop passage on which the channel 18 andthe solvent supplying section 21 are provided.

In the corners of the bottom of the main body 16, which surround thewafer suction table 17 (wafer 1), four exhaust ports 19 a to 19 d aremade to control the air flow in the main body 16. The exhaust ports 19 ato 19 d are connected to an exhaust device (not shown) by flow ratecontrol valves 70 a to 70 d, respectively. The flow rate control valves70 a to 70 d are connected to an exhaust control section 71. The exhaustcontrol section 71 controls the flow rate control valves 70 a to 70 dindividually. For example, the air may be exhausted through only twoexhaust ports 19 a and 19 b, thereby causing the air to flow in aparticular direction in the main body 16. The flow of the solventevaporated from the resist solution is thereby controlled to prevent thesolvent from evaporating to excess as will be described later.

The suction table 17 has a wafer holding section 23 for holding thewafer 1 on the upper surface and a Zθ drive mechanism 24 for driving thewafer holding section 23 in Zθ direction. A vacuum device (not shown) isconnected to the wafer holding section 23 so that the section 23 mayperform vacuum chucking of the wafer 1 placed on its upper surface. TheZθ drive mechanism 24 is connected to a Z-positioning/notch-alignmentsection 25 as is illustrated in FIG. 1. TheZ-positioning/notch-alignment section 25 actuates the Zθ drive mechanism24 when the wafer holder 6 moves to the wafer load/unload section L,making the Zθ drive mechanism 24 perform Z-direction operation totransfer the wafer 1 and θ-operation to achieve notch alignment.

An ultrasonic vibrator 73 is secured to the wafer suction table 17, forvibrating the wafer 1 held on the table 17 by virtue of vacuum suction.The ultrasonic vibrator 73 is connected to an agitation generatingsection 74. The agitation generating section 74 applies vibration to thewafer 1 after the wafer 1 has been coated with the resist solution.Agitation is thereby applied to the resist solution film, rendering thesurface of the film flat. The agitation works very well, particularlywhen the resist solution is applied in a single-stroke writing manner,because the surface of the resultant film of resist solution is not flatin most cases unlike in the spin coating method.

In the wafer holder 6, a member drive mechanism 27 is provided forholding the mask member 4 right above the wafer 1 and for driving themask member 4 in the direction of arrow A (Y direction) to move themember 4 into and from the wafer holder 6. The mask member 4 covers thewafer 1, except the circuit-forming region la, as shown in FIG. 3, andtherefore prevents the resist solution from being applied to theperipheral part of the wafer 1. The mask member drive mechanism 27 movesthe mask member 4 dirty with the resist solution, to a mask washingapparatus 42 from the resist solution applying apparatus through thepassages 38 and 39 made in the wafer holder 6 and frame 5, respectively,as is illustrated in FIG. 2.

The mask washing apparatus 42 has a washing mechanism (not shown) andholds a spare mask member 4′. The mask washing apparatus 42 receives themask member 4 dirty with the resist solution, from the resist solutionapplying apparatus. The spare mask member 4′, washed clean, istransported from the mask washing apparatus 42 to the resist solutionapplying apparatus. The mask member drive mechanism 27 receives the maskmember 4′ and positions the same with respect to the wafer 1.

As mentioned above, the temperature-controlled top plate 7 covers thewafer holder 6. As shown in FIG. 1, a linear heater 26, for example, isembedded in the top plate 7 for heating the top plate 7 to apredetermined temperature. Thus heated, the top plate 7 performs twofunctions.

The first function is to maintain and control the atmosphere of solvent,surrounding the wafer 1. When the resist solution is applied in a mannerof so-called “single-stroke writing”, it is applied in a slender streamas will be described later. The solvent contained in the solution istherefore likely to evaporate. Hence, it is required that the solventatmosphere around the nozzle unit 2 and over the upper surface of thewafer 1 be always controlled to have a constant concentration.

The top plate 7 is heated to the predetermined temperature, thuspreventing the solvent in the solvent atmosphere from coagulating. Inparticular, the solvent is prevented from condensing into drops on thelower surface of the top plate 7. This is how the top plate 7 controlsthe concentration of the solvent atmosphere.

The second function is to heat the nozzle unit 2 so as to preventclogging in the nozzle unit 2 and interruption of the resist solutionstream. As will be explained later in detail, the nozzle unit 2 needs toapply the resist solution in a slender stream and continuously, withoutinterruption. The discharge hole of the unit 2 is much smaller than thatof the resist solution nozzle of the conventional type. Clogging in thedischarge hole of the nozzle unit 2 must, therefore, be preventedeffectively.

The top plate 7 is located near the distal end of the nozzle unit 2.Thus located, the top plate 7 heats the nozzle unit 2 and maintain thesame at an appropriate temperature, thereby effectively preventingclogging in the discharge hole of the nozzle unit 2.

Thanks to the first function, a prescribed atmosphere of solvent ismaintained and controlled around the nozzle unit 2. As a result, thesolvent is effectively prevented from evaporating immediately after theresist solution has been applied, thus avoiding clogging in thedischarge hole and also maintaining the resist solution at a constantviscosity. Interruption of the resist solution stream is therebyprevented.

As shown in FIG. 2, the top plate 7 is provided above the resistsolution applying section R only and covers the wafer holder 6. The topplate 7 needs to have such a size as to cover the wafer holder 6 even ifthe wafer holder 6 is moved the longest distance in the Y direction tocoat the wafer 1 with the resist solution.

As indicated above, the slit 7 a is made in the top plate 7, extendingin the X direction, for allowing the nozzle unit 2 to move in the Ydirection. The slit 7 a has a length corresponding to the diameter ofthe wafer 1 and has a width large enough to allow passage of the nozzleunit 2.

The linear heater 26 embedded in the top plate 7 is connected to atop-plate temperature control section 28. The control section 28controls the linear heater 26.

As shown in FIG. 1, the nozzle unit 2 is held by a linear slidingmechanism 29 that stretches in the top of the frame 5 and extends in theX direction. The linear sliding mechanism 29 has an X rail 30, a slider31 slidably mounted on the X rail 30, a ball screw 32 for driving theslider 31, and an X drive motor 33 for rotating the ball screw 32.

The nozzle unit 2 is held by the slider 31 at a position where itopposes the slit 7 a made in the top plate 7. The lower end portion ofthe nozzle unit 2 extends downwards into the wafer holder 6 through theslit 7 a. It is desired that a Z drive mechanism (not shown) that candrive the nozzle unit 2 in the Z direction be provided on the slider 31to pulling the nozzle unit 2 out of the slit 7 a so that the nozzle unit2 may be regularly washed.

The X drive motor 33 for driving the nozzle unit 2 in the X directionand the Y drive motor 12 for driving the wafer 1 in the Y direction areconnected to a nozzle-wafer drive section 34. The nozzle-wafer drivesection 34 drives the X drive motor 33 and the Y drive motor 12 insynchronism, thereby to move the nozzle unit 2 over the wafer 1 in aprescribed route.

The nozzle-wafer drive section 34 operates in accordance with thesolution application route and relative speed which have been set by theroute-speed setting section 36 provided in a central control section 35.The route-speed setting section 36 determines a solution applicationroute on the basis of the wafer size (the size of the circuit-formingregion 1 a), the basic pattern of solution application route, therequired amount of resist solution to apply, and the like, which arestored in an application condition file 37.

The wafer sizes available are 6 inches, 8 inches, 12 inches, and thelike. There are various basic patterns of solution application route,among which are a zigzag route (FIG. 3), a spiral route, and the like.The amount of resist solution to apply is determined from the desiredthickness of the film and the area to coat with the resist solution. Therelative speed, which is determined from the amount of solution to applyand the time of applying the solution, is very important because it isgreatly related with the thickness of the film.

The route-speed setting section 36 may automatically set the conditionsof applying the resist solution. Alternatively, an operator may selectdesired conditions and input them into the route-speed setting section36.

The central control section 35 is a computer system for accomplishingcentral control of all components of the resist solution applyingapparatus, including those not illustrated in FIG. 1.

The nozzle unit 2 has, for example, the structure shown in FIG. 4. Thenozzle unit 2 has a double-pipe structure. The inner pipe is a resistsolution nozzle 40 for applying the resist solution in the form of aslender stream. The outer pipe is a solvent nozzle 41 for applying asolvent in the form of mist, along the outer circumferential surface ofthe resist solution nozzle 40.

The resist solution nozzle 40 is made of, for example, stainless steel.Its discharge hole 40 a has an extremely small diameter of 10 μm to 200μm. The resist solution contains solvent, like those generally used inthis field of art. Since the discharge hole 40 a has an extremely smalldiameter, the ratio of its inner surface area to its volume is large.Consequently, the solvent is likely to evaporate, clogging the dischargehole 40 a.

To prevent the clogging effectively, the discharge hole 40 a is onlylong enough to form a resist solution stream having a stable diameter,and the resist solution is supplied into the hole 40 a through asupplying hole 40 b having a relatively large diameter of, for example,about 2 mm.

As shown in FIG. 1, the resist solution nozzle 40 is connected by aresist solution temperature control section 44 to a resist solutionsupplying section 45. To apply the resist solution in a single-strokewriting manner it is important to discharge the resist solution in astream as slender as possible, without a break, while moving the nozzleunit 2 at regular pitches, so as to form a thin film having a uniformthickness.

The maximum speed of discharging the resist solution is determined bythe water-head pressure of the discharge hole 40 a. To discharge theresist solution under a high pressure to attain the maximumsolution-discharging speed, the resist solution supplying section 45 hasa positive displacement pump, such as a cylinder pump, which forces outthe resist solution.

Further, the resist solution applied onto the wafer 1 spreads to someextent, depending on its viscosity. Thus, the pitch at which the nozzleunit 2 should be moved in the Y direction can be determined on the basisof the viscosity of the solution, and the solution application route isdetermined. Once the solution application route has been determined, therelative speed at which the nozzle unit 2 should be driven is determinedfrom the time of applying the resist solution (obtained from thesolution applying rate and the amount of solution to be discharged). Inthis apparatus, the relative drive speed of the nozzle unit 2 (e.g., 500mm/s to 1 m/s) is lower than the solution-discharging speed (e.g., 2m/s).

In the case where the nozzle unit 2 is driven while discharging theresist solution, care must be taken so that a slender stream of resistsolution should not be interrupted. According to this invention, toprevent interruption of the resist solution stream, the resist solutiontemperature control section 44 controls the temperature of the resistsolution and the top plate 7 controls this temperature even before thesolution is applied. The resist solution temperature control section 44is a water jacket that contains temperature-adjusting water heated to aprescribed temperature.

The solvent nozzle 41 is connected to a solvent-temperatureadjusting/solvent supplying section 46 shown in FIG. 1. Thesolvent-temperature adjusting/solvent supplying section 46 controls thetemperature of the solvent and supplies the solvent to the solventnozzle 41. The solvent nozzle 41 applies the solvent, adjusted to apredetermined temperature, in the form of mist. As shown in FIG. 4, themist of solvent envelopes the stream of resist solution that is beingdischarged from the resist solution nozzle 40. The evaporation of thesolvent from the resist solution is thereby inhibited, maintaining theviscosity of the resist solution at a constant value and preventinginterruption of the resist solution stream.

In addition, the viscosity of the resist solution applied onto the wafer1 would not abruptly decrease since the wafer 1 remains in a constantatmosphere as described above. Thus, interruption of the resist solutionstream is prevented on the wafer 1 and the spread of resist solution ispromoted.

The solvent atmosphere in the wafer holder 6 is generally controlled bythe evaporation of solvent from the solvent channel 18, the temperaturecontrol achieved by the top plate 7, and the discharge of solvent mistfrom the solvent nozzle 41. (Namely, an atmosphere control mechanism isprovided according to the present invention.) This control of thesolvent atmosphere is managed by an atmosphere management section 47provided in the central control section 35.

The step of applying the resist solution, performed by this resistsolution applying apparatus, will be explained next.

(1) First, a semiconductor wafer 1 is loaded into the resist solutionapplying apparatus. The Y drive motor 12 is driven, positioning thewafer holder 6 at the wafer load/unload section L located at the otherend of the frame 5.

The wafer 1 is transferred to the wafer load/unload section L, whileheld by the main arm (not shown) provided for transferring wafers. TheZθ drive mechanism 24 is actuated, moving the wafer holding section 23of the wafer suction table 17, up or down, whereby the wafer 1 is placedonto the wafer suction table 17. Then, the suction mechanism (not shown)is actuated, whereby the wafer suction table 17 holds the wafer 1 byvirtue of a suction force.

Now that the wafer 1 held by virtue of a suction force, notch alignmentis achieved by the Z-positioning/notch-alignment section 25. Alight-emitting device and a light-receiving sensor are arranged on theframe 5, at specified positions whrer they oppose the peripheral part ofthe wafer 1. The Zθ drive mechanism 24 rotates the wafer 1. Themechanism 24 stops the wafer 1 the moment the light-receiving sensordetects the notch 1 b (FIG. 3) made in the peripheral part of the wafer1, that is, after the wafer 1 has rotated through an angle. When notchalignment is thus accomplished, the wafer holding section 23 is drivendownwards, and the wafer 1 is moved into the wafer holder 6. Int hewafer holder 6 the wafer 1 is locked not to rotate.

Next, the Y drive motor 12 is driven, moving the wafer holder 6 andpositioning the same at the resist solution applying section R. Afterthe wafer holder 6 has been positioned at the resist solution applyingsection R, the mask member drive mechanism 27 receives the mask member 4from the mask washing apparatus 42 and holds the mask member 4 above thewafer 1.

(2) While the wafer 1 being loaded, the atmosphere management section 47provided in the central control section 35 keeps managing the solventatmosphere. That is, the solvent in the solvent channel 18 of the waferholder 6 has already been controlled in temperature and surface level.Further, the top plate 7 has been heated to a prescribed temperature,thus preheating the nozzle unit 2. Still further, the solvent isdischarged from the solvent nozzle 41, preventing the resist solutionfrom drying in the discharge hole 40 a of the resist solution nozzle 40and, hence, avoiding clogging of the discharge hole 40 a.

(3) When the wafer 1 is positioned at the resist solution applyingsection R, the central control section 35 causes the nozzle unit 2 andthe wafer 1 to move relative to each other in accordance with thesolution application route, relative drive speed and other conditionswhich have been set by the route-speed setting section 36, therebyapplying the resist solution to the wafer 1.

To move the nozzle unit 2 along the route shown in FIG. 3, it isnecessary to decelerate and accelerate the nozzle unit 2 at each turningpoint in the X direction. This may result in variation in the thicknessof resist solution film. In order to avoid such variation, the nozzleunit 2 is turned back above the mask member, that is, outside thecircuit-forming region la of the wafer 1. Thus, the nozzle unit 2 ismoved at a constant speed over the entire the circuit-forming region 1a.

The film of the resist solution applied onto the wafer 1 is therebyadjusted in accordance with the diameter of the solution stream, therelative speed of the nozzle unit 2 and the spread of the resistsolution on the wafer 1. As a result, a solution film having a uniformthickness is formed on the circuit-forming region 1 a of the wafer 1.

At this time, the exhaust control section 71 operates, controlling theairflow around the wafer 1, thereby inhibiting the evaporation ofsolvent from the resist solution applied to the wafer 1. To move thenozzle unit 2 in the Y direction, for example, from the left to theright in FIG. 2, air is exhausted through only the exhaust ports 19 aand 19 b provided at the upstream in the Y direction, not through theother exhaust ports 19 a and 19 d. The solvent evaporated from theresist solution is thereby guided to the resist solution already appliedto the wafer 1, whereby a solvent atmosphere covers the surface of theresist solution film. This effectively prevents the solvent fromevaporating to excess from the resist solution already applied to thewafer 1.

After the application of resist solution has completed, the agitationgenerating section 74 actuates the ultrasonic vibrator 73 secured to thewafer suction table 17. The vibrator 73 vibrates the wafer 1 at afrequency of the ultrasonic frequency band. The resist solution appliedto the wafer 1 is thereby agitated, whereby the surface of the solutionfilm become flat.

(4) Upon completion of the above-mentioned sequence of operations, themask member 4 got dirty with the resist solution is ejected into themask washing apparatus 42. Then, the wafer holder 6 is moved away fromthe resist solution applying section R to the wafer load/unload sectionL. At the wafer load/unload section L, the wafer holding section 23 ismoved up or down, thereby transferring the wafer 1 to the main arm (notshown).

The structure described above can be advantageous in the followingrespects.

First, the use efficiency of resist solution can be much increased to,in some cases, nearly 100% since the resist solution is applied in asingle-stroke writing manner, without rotating the wafer 1.

In the spin coating method, generally employed as a method of applyingresist solution, the resist solution is spun off in droplets from theperipheral part of the wafer, inevitably wasted in a large amount,because the wafer is rotated at high speed. In one instance, only 10% ofthe resist solution applied onto the wafer contributes to the formationof a resist film.

In this method, the resist solution may be applied also to theperipheral part of the wafer, in which no circuits will be formed. Theresist solution applied to this region usually needs to be removed by adedicated apparatus called “edge remover,” immediately after the step ofapplying the resist solution.

By contrast, the resist solution need not be removed after the step ofapplying the resist solution in the resist solution applying apparatusaccording to this invention. This is because the use efficiency ofresist solution is greatly increased in the apparatus according to theinvention.

Second, interruption of the resist solution stream can be prevented,making it possible to form a film of solution that is thin and uniform.

That is, to apply resist solution is applied in a single-stroke writingmanner, it is necessary to apply the solution in the form of as slendera stream as possible and to prevent the stream of the solution frombeing interrupted. Further, it is probable that the stream of solutionis interrupted if the solution changes in its viscosity while beingdischarged. It is also probable that the solution-applying nozzle isclogged. These undesired events should be prevented, too.

With this invention it is possible to control, with high precision, theconcentration of the solvent atmosphere that envelops the stream ofresist solution, in order to prevent interruption of the stream ofresist solution. Hence, the viscosity of the stream can be maintainedconstant, however slender the stream is. Thus, the stream of resistsolution can be prevented from being interrupted.

Particularly, the solvent can be prevented from evaporating from theresist solution and from changing in terms of viscosity even immediatelyafter the resist solution has been discharged from the nozzle unit 2.This is because the solvent nozzle 41 provided is made integral with thenozzle unit 2. Further, interruption of the stream of resist solutioncan be prevented by controlling, with high precision, the concentrationof the solvent atmosphere and the heating of the nozzle unit 2 by theuse of the top plate 7.

Third, since the resist solution can be prevented from spinning off indroplets, forming of particles can be effectively prevented.

That is, in the spin coating method, the wafer must be rotated in a cupso that the cup may receive the resist solution spinning off in dropletsfrom the wafer. The solution sticking to the cup form particles, whichmay contaminate the wafer. It is therefore necessary to wash the cupfrequently.

By contrast, in the resist solution applying apparatus according to thisinvention, the stream of resist solution, which is applied at a time,can have a very small diameter, preventing the solution from leaving thewafer. In addition, since the wafer 1 is not rotated, the solutionscarcely spins off in droplets. Such a cup as is required in the spincoating method need not be provided. Nor will it be necessary to washsuch a cup.

Fourth, the mask member 4 covers the peripheral part of the wafer 1, andthe nozzle unit 2 starts and stops applying the resist solution andrepeatedly changes its moving direction only while it is moving abovethe mask member 4. Thus, the nozzle unit 2 can be moved at a constantspeed, that is, neither accelerated nor decelerated while moving overthe circuit-forming region 1 a of the wafer 1. This helps form a resistsolution film having a uniform thickness.

In this case, the mask member 4 gets dirty with the resist solution.Nevertheless, the mask member 4 can be washed since the mask washingapparatus 42 is provided beside the resist solution applying apparatus.Further, the throughput of applying the resist solution would not bereduced because the mask washing apparatus 42 moves the mask member 4′,already washed, to the position above the wafer 1, at the same time itreceives the mask member 4, got dirty with the solution, from thatposition.

Fifth, the apparatus of the invention can reliably apply the resistsolution to the entire circuit-forming region 1 a of the wafer 1. Thisrenders it unnecessary to perform a pre-wetting step (i.e., applying asolvent, such as thinner, to the surface of the wafer 1 before applyingthe resist solution thereto). The film-forming step can be therebysimplified.

(Coating/Developing System)

It is desirable to apply this resist solution applying apparatus to thecoating/developing system shown in FIGS. 5 to 7.

As shown in FIG. 5, the coating/developing system comprises a cassettesection 50, a process section 51, and an interface section 52. In thecassette section 50, wafers 1 are sequentially taken from a cassette CR.In the process section 51, the resist solution is applied to a wafer 1and the resist film formed on the wafer 1 is developed. At the interfacesection 52, the wafer 1 coated with the resist solution is transferredto and from an exposure apparatus (not shown).

The cassette section 50 comprises four projections 60 a for positioningand holding cassettes CR and a first sub-arm mechanism 61 for taking awafer 1 from the cassette CR held by any projection 60 a. The sub-armmechanism 61 can rotate the wafer 1 in direction, thus changing theorientation of the wafer 1 and also can transfer the wafer 1 to a mainarm mechanism 62 provided in the process section 51.

Wafers 1 are transferred between the cassette section 50 and the processsection 51 through the process units of a third group G3. As shown inFIG. 7, the process units of the third group G3 are arranged one uponanother, forming a vertical column. More precisely, the third processunit group G3 is composed of a cooling unit (COL) for cleaning a wafer1, an adhesion unit (AD) for rendering the wafer 1 hydrophobic to bewell wetted with resist solution, an alignment unit (ALIM) for aligningthe wafer 1, an extension unit (EXT) for holding the wafer 1 at a waitposition, two pre-baking unit (PREBAKE) for heating the wafer 1 beforeexposure process, and two post-baking units (POBAKE) for heating thewafer 1 after the exposure process, which are arranged one on another inthe order they are mentioned.

The wafer 1 is transferred to the main arm mechanism 62 through theextension unit (EXT) and the alignment unit (ALIM).

As shown in FIG. 5, the first to fifth process unit groups G1 to G5 ofprocess units, including the third process unit group G3, surround themain arm mechanism 62. Like the third process unit group G3, the otherprocess unit groups G1, G2, G4 and G5 are each composed of several unitsarranged one upon another.

Two resist solution applying apparatuses (COT) according to thisinvention are included in the first process unit group G1 and the secondprocess unit group G2, respectively, as is illustrated in FIG. 6. Twodeveloping apparatuses (DEV) are mounted on the resist solution applyingapparatuses (COT), respectively.

As shown in FIG. 7, the main arm mechanism 62 comprises a hollowcylindrical guide 69 that extends vertically and a main arm 68 that canbe driven vertically along a guide 69. The main arm 68 can also rotatein a horizontal plane and can be driven back and forth. Thus, when themain arm 68 is moved up or down, a wafer 1 can have access to anyprocess unit provided in any one of the process unit groups G1 to G5.

The main arm mechanism 62 receives a wafer 1 from the cassette section50 through the extension unit (EXT) of the third process unit group G3and transports the wafer 1 into the adhesion unit (AD) of the thirdprocess unit group G3. In the adhesion unit (AD) the wafer 1 is renderedhydrophobic. Then, the mechanism 62 transports the wafer 1 from theadhesion unit (AD) into the cooling unit (COL), in which the wafer 1 iscooled.

The wafer 1, thus cooled, is made to oppose the resist applyingapparatus (COT) of the first process unit group G1 (or second processunit group G2) and is moved into this resist applying apparatus (COT).The wafer 1 can be thereby loaded into the wafer load/unload section Lof the resist applying apparatus according to the present invention.

In the resist applying apparatus (COT), resist solution is applied onthe wafer 1 in a single-stroke writing manner as described above. Themain arm mechanism unloads the wafer 1 from the wafer load/unloadsection L and transfers the wafer 1 to the interface section 52 throughthe fourth press unit group G4.

As shown in FIG. 7, the fourth process unit group G4 comprises a coolingunit (COL), an extension/cooling unit (EXT/COL), an extension unit(EXT), a cooling unit (COL), two pre-baking units (PREBAKE), and twopostbacking units (POBAKE), which are arranged one upon the other in theorder they are mentioned.

The wafer 1 taken from the resist applying apparatus (COT) is firstinserted into the pre-baking unit (PREBAKE), in which the solvent(thinner) is evaporated from the resist solution, thus drying the wafer1. The drying of wafer may be accomplished by, for example, vacuumdrying method. That is, the wafer 1 is inserted into the pre-baking unit(PEBAKE) or a chamber other than the pre-baking unit, and the pressuretherein may be reduced to remove the solvent (or to dry the resistsolution).

Note that, the pre-baking unit (PREBAKE) for drying the wafer 1 may belocated inside the resist applying apparatus (COT).

Next, the wafer 1 is cooled in the cooling unit (COL) and transferredvia the extension unit (EXT) to a second sub-arm mechanism 54 that isprovided in the interface section 52.

The second sub-arm mechanism 54 holds the wafers 1 it has' received,into the cassette CR, one after another. The interface section 52transfers the cassette CR containing the wafers 1, to the exposureapparatus (not shown), and receives the cassette CR containing thewafers 1 which have undergone the exposure process.

Each wafer 1 subjected to the exposure process is transferred via theprocess units of the fourth group G4 in the reverse order, to the mainarm mechanism 62. The main arm mechanism 62 inserts the wafer 1, whichhas been exposed to light, into the post-baking unit (POBAKE), ifnecessary. Then, the mechanism 62 inserts the wafer 1 into thedeveloping apparatus (DEV), in which the wafer 1 is subjected todeveloping process. The wafer 1, which has undergone the developingprocess, is transported to any baking unit, heated and dried therein,and transferred to the cassette section 50 through the extension unit(EXT) of the third process unit group G3.

The fifth process unit group G5 is selectively provided. In the presentinstance, it is composed in the same way as the fourth process unitgroup G4. The fifth process unit group G5 is movably supported on rails55, thereby facilitating the maintenance of the first to fourth processunit groups G1 to G4.

If the film forming apparatus according to the invention is used in thecoating/developing system shown in FIGS. 5 to 7, a plurality of waferscan be processed simultaneously, whereby the coating/developing step canbe conducted on the wafers 1 with high efficiency. In addition, theinstallation area for the system can be remarkably reduced because theprocess units are arranged, one upon another, forming vertical columns.

The film forming apparatus according to the first embodiment can be, ofcourse, used in systems other than the coating/developing systemdescribed above. Moreover, the film forming apparatus can be modified invarious ways, within the scope of the present invention.

First, the resist-solution applying nozzle unit 2 is not limited to theone illustrated in FIG. 4. Rather, the structure 2′ shown in FIG. 8, forexample, may be used instead. In FIG. 8, the components identical tothose shown in FIG. 4 are designated at the same reference numerals.

The nozzle unit 2′ is of double-pipe structure like the nozzle unit 2 ofFIG. 4. The inner pipe is a resist solution nozzle 40 for applying theresist solution in the form of a slender stream, and the outer pipe is asolvent nozzle 41 for applying a solvent in the form of mist. However, asolvent pan 70 is provided at the lower end of the solvent nozzle 41,for accumulating the solvent.

This structure can not only attain the same advantages as the nozzleunit 2 of FIG. 4, but also minimize the changes in the atmosphere ofsolvent. In other words, the atmosphere of solvent stabilizes.

Second, the solution application route is not limited to that adopted inthe first embodiment (FIG. 3). Rather, it may be such a spiral one as isshown in FIG. 9. If this is the case, it is preferable that the nozzleunit 2 be moved in the radial direction of the wafer 1 (e.g., the Xdirection) while rotating the wafer 1 at low speed (e.g., 20 to 30 rpm).

In this case, too, it is important to maintain the speed of the wafer 1,relative to the nozzle unit 2, at a constant value. If the nozzle unit 2is moved at a constant speed, for example, the rotation speed of thewafer 1 must be gradually lowered as the nozzle unit 2 approaches theperipheral edge of the wafer 1. On the other hand, if the wafer isrotated at a constant speed, the speed of the nozzle unit 2 must begradually lowered as the nozzle unit 2 moves toward the peripheral edgeof the wafer 1.

Third, to form a film of resist solution, which has a uniform thickness,the resist solution may be applied twice to the wafer 1, first in afirst direction and then in a second direction, as is illustrated inFIG. 10. In this case, both the point START at which the application ofsolution is started and the point END at which the application ofsolution is terminated are located above the mask member 7. Thus, thenozzle unit 2 can be moved always at a constant speed over the wafer 1,thereby forming a film of resist solution that has a uniform thickness.

Fourth, in the first embodiment described above, the wafer 1 isintermittently moved in the Y direction at a certain pitch and thenozzle unit 2 is driven back and forth in the X direction. The method ofmoving the wafer 1 and nozzle unit 2 is not limited to this one.Instead, the wafer 1 may be moved in the X and Y directions, while thenozzle unit 2 is retained at a fixed position. In this case, the topplate 7 need not have a slit 7 a, which enhances the insulationeffectiveness.

Further, the actual mechanisms for driving the nozzle unit 2 and waferholder 6 are not limited to those used in the first embodiment. Needlessto say, other drive mechanisms, such as belt drive mechanisms, may beemployed instead.

Fifth, any solution other than the resist solution used in the firstembodiment may be applied to the wafer 1 to form a film thereon. Forexample, a solution for forming an interlayer insulating film, asolution for forming a highly conductive film, a ferroelectric solution,sliver paste, or the like may be applied in place of the resistsolution.

Sixth, the substrate to be processed is a semiconductor wafer 1 in theembodiment described above. Nonetheless, the substrate may be an LCDsubstrate or an exposure mask.

Further, although one nozzle unit is used in the above-describedembodiment, two or more nozzle units may be arranged side by side. Ifso, it is possible to shorten the time for coating the wafer 1 with theresist solution.

Seventh, the mask member 4 used in the first embodiment may not be used.In this case, it suffices to provide a container, such as a cup, belowthe wafer 1, to receive the residual resist solution.

Eighth, the technique of agitating the film of resist solution to imparta flat surface thereto is not limited to the method performed in thefirst embodiment, i.e., the use of the ultrasonic vibrator 73 secured tothe wafer suction table 17.

For example, no vibrator may be used, and the wafer 1 may be moved inthe Y direction by means of a ratchet mechanism, thereby to agitate thesolution film formed on the wafer 1. Alternatively, any other method maybe employed to agitate the solution film formed on the wafer 1.

Ninth, the mask member 4 having an opening exposing the circuit-formingregion 1 a of the wafer may be moved in the Y direction along with thenozzle unit 2, not retained immovable with respect to the wafer 1 as inthe first embodiment described above.

In this case, the mask member must be one whose opening changes in sizein accordance with the back-and-forth stroke of the nozzle unit 2 movingin the X direction. For instance, a mask member 80 of the structureillustrated in FIG. 11A may be employed.

The mask member 80 shown in FIG. 11A has a pair of solution pans 81 thatare spaced apart in the X direction. The solution pans 81 can be drivento change the distance between them, in accordance with the X-directionstroke of the nozzle unit 2. Thus, the pans 81 are located always at thetwo turning points of the nozzle unit 2, respectively.

That is, the solution pans 81 are connected to a pan-driving mechanism82 by L-shaped arms 83. The pan-driving mechanism 82 is secured to thelinear sliding mechanism 29 shown in FIG. 2 and can move in the Ydirection together with the linear sliding mechanism 29. The pan-drivingmechanism 82 may comprise, for example, a stepping motor and a lineargear.

The pan-driving mechanism 82 is also connected to the central controlsection 35 and operates in accordance with the solution applicationroute and the relative speed, both set by the route-speed settingsection 36. That is, the distance between the solution pans 81 iscontrolled to a value substantially equal to the X-direction stroke ofthe nozzle unit 2, i.e., the width of the circuit-forming region 1 a.

The solution pans 81 have, for example, the structure shown in FIGS. 11Band 11C. FIG. 11B is a vertical sectional view, and FIG. 11C is a frontview.

Each solution pan 81 has a channel-shaped main body 85 that opens at thetop. The main body has two side walls 85 a, which stand from the uppersurface of the main body 85 and which extend in the Y direction. Thewalls 85 a prevent the resist solution from dripping from the long sidesof the solution pan 81. No walls stand from the distal end of the mainbody 85. The distal end of the main body 85 is inclined downwards andtoward the proximal end of the main body 85, forming an inclined surface85 b. The main body 85 has a first suction hole 86, which opens at theinclined surface 85 b to draw the resist solution, which may otherwisedrip along the inclined surface 85 b.

The upper surface of the main body 85 is gently inclined downwards tothe proximal end. The proximal end of the main body 35 has a secondsuction hole 87 through which the resist solution can be drawn from theupper surface of the main body 85.

The first and second suction holes 86 and 87 are connected to solutiondischarge tubes 88 and 89, respectively. The resist solution thesolution pan 81 has received is forcedly discharged.

The solution pans 81 may be washed with solvent, such as thinner, in theframe 5 or the cup-shaped main body 16.

The mask member 80 shown in FIG. 11A is smaller than the mask memberused in the first embodiment described above and can be washed withinthe apparatus. Hence, the mask member 80 serves to miniaturize theapparatus as a whole.

The mechanism for driving the solution pans 81 is not limited to the onedepicted in FIG. 11A. For example, the distance between the pans 81 maybe adjusted by using, as shown in FIG. 11D, a guide plate 90 in whichtwo profiling cams 91 are cut. Each profiling cam 91 has the same shapeas the peripheral edge of the circuit-forming region 1 a of the wafer 1.The two cam followers 92 protrude downwards from the pans 81 areinserted in the profiling cams 91. The cam followers 92 are driven alongthe profiling cams 91, respectively, whereby the distance between thesolution pans 81 is controlled.

(Second Embodiment)

The second embodiment of the present invention will be described, withreference to FIGS. 12 to 17. The second embodiment is a resist solutionapplying apparatus, which is preferably used also in thecoating/developing system illustrated in FIGS. 5 to 7. Thecoating/developing system will not be described below since it has beendescribed above in detail.

The film forming apparatus according to this embodiment is the same asthe first embodiment in that resist solution 3 is applied to only thecircuit-forming region 1 a of a wafer 1 in a so-called single-strokewriting manner as illustrated in FIG. 12.

In the second embodiment, however, the wafer 1 is turned upside down andheld, with the circuit-forming region 1 a facing downwards as shown inFIG. 12, and the resist solution 3 is discharged upwards from a solutionapplying nozzle unit 2 to coat the region 1 a with the resin solution.

Also in this embodiment, a mask member 4 is arranged right below thewafer 1, covering the peripheral part of the wafer 1, not covering thecircuit-forming region 1 a. The solution applying nozzle unit 2 isdriven back and forth in the X direction, while being intermittentlymoved in the Y direction at a certain pitch, thereby coating only thecircuit-forming region 1 a with the resist solution.

The structure of this resist applying apparatus, which is a film formingapparatus, will be described below in detail.

FIGS. 13A and 13B are partial sectional views of the resist applyingapparatus, and FIG. 14 is a plan view thereof.

As shown in FIG. 14, this apparatus has a main arm mechanism 110, areversing mechanism 111 for turning upside down the wafer 1 transportedby the main arm mechanism 110, a sub-arm mechanism 112 for receiving thewafer 1 thus turned and transport the same in the direction of arrow α,a solution applying mechanism 113 for applying resist solution to thewafer 1 transported by the sub-arm mechanism 112 and held at apredetermined position, and a mask member washing mechanism 113 forremoving the mask member 4 form the resist solution applying mechanism113 and washing the mask member 4.

As shown in FIG. 13A, the resist solution applying mechanism 113 has aframe 116 and a nozzle unit drive mechanism 117 provided in the frame116, for driving the nozzle unit 2 in X, Y and Z directions. The nozzleunit 2 is arranged, with the discharge port turned upwards, and opposesthe wafer 1 held by the sub-arm mechanism 112.

The sub-arm mechanism 112 holds the wafer 1 as is illustrated in FIG.13B. The sub-arm mechanism 112 has a pair of arms 120 that can open andclose in the direction of arrow 113 (FIG. 13B) and holding pads 121secured to the inner surfaces of the arms 120, for holding the wafer 1without touching the circuit-forming region 1 a of the wafer 1. Forexample, four holding pads 121 are arranged along the circumference ofthe circle defined by the arms 120, as is illustrated in FIG. 14.

The frame 116 is shaped as shown in FIG. 13A, defining a space in whichthe nozzle unit 2 can move. A solvent channel 122 is provided in thisspace so that a solvent atmosphere may envelop the nozzle unit 2. Thesolvent channel 122 is filled with solvent that is controlled intemperature and surface level. The solvent evaporates, forming a solventatmosphere having a predetermined concentration and enveloping the wafer1. The above-mentioned mask member 4 is removably held at the top of theframe 116.

The nozzle unit drive mechanism 117 has a Y-direction drive mechanism125 secured to the lower surface of the frame 116, an X-direction drivemechanism 126 held by the Y-direction drive mechanism 125 and able tomove in the Y direction, and a Z-direction drive mechanism 127 held bythe X-direction drive mechanism 126 and able to move in the Z direction.The nozzle unit 2 is attached to the Z-direction drive mechanism 127 andcan be moved in the X, Y and Z directions to be positioned. The drivemechanisms 125 to 127 may be of any appropriate type. They may beball-screw drive mechanisms or belt drive mechanisms.

As illustrated in FIG. 14, one end portion of the Y-direction drivemechanism 125 extends toward the lower end of the diagram, from thespace where the resist solution is applied. The Y-direction drivemechanism 125 is designed to drive the nozzle unit 2 and position thesame at a nozzle unit station 129.

FIG. 15 shows the nozzle unit 2 held at the nozzle unit station 129.With reference to FIG. 15, the structures of the nozzle unit 2 andnozzle unit station 129 will be described.

The nozzle unit 2 comprises a nozzle 130 and a nozzle holder 131 holdingthe proximal end of the nozzle 130.

The nozzle 130 is made of, for example, stainless steel. Its dischargehole 130 a has an extemely small diameter of 10 μm to 200 μm. The resistsolution to be discharged from the hole 130 a contains solvent, likethose generally used in this field of art. Since the discharge hole 130a has an extremely small diameter, the ratio of its inner surface areato its volume is large. Consequently, the solvent is likely toevaporate, clogging the discharge hole 130 a.

To prevent the clogging effectively, the discharge hole 130 a is onlylong enough to form a resist solution stream having a stable diameter,and the resist solution is supplied into the hole 130 a through asupplying hole 130 b having a relatively large diameter of, for example,about 2 mm.

The nozzle holder 131 has a resist solution passage 133 that connectsthe nozzle 130 and a resist solution pipe 132. Further, the nozzleholder 131 has a solvent bypass passage 134 for supplying a solvent suchas thinner into the nozzle 130.

The bypass passage 134 is opened while the nozzle unit 2 is held at thenozzle unit station 129. Thus, the solvent is continuously passedthrough the discharge hole 130 a of the nozzle 30, thereby preventingclogging of the discharge hole 130 a. The solvent discharged from thenozzle 130 evaporates in the nozzle unit station 129, forming a solventatmosphere of a prescribed concentration, which envelops the distal endof the nozzle 130.

The nozzle unit station 129 has a nozzle insertion hole 136 into whichthe distal end of the nozzle 130 can be inserted. In the nozzle unitstation 129 a solvent channel 137 is provided to receive the solventdischarged from the nozzle 130. The solvent accumulated in the solventchannel 137 is sequentially drained through a draining pipe 138.

Next, this resist solution applying apparatus will be described withreference to FIG. 15.

First, the resist solution pipe 132 is connected to a resist solutionsupplying section 142. A solution supply valve 140 and a resist solutiontemperature control section 141 are provided on the resist solution pipe132.

When the resist solution is applied in a manner of single-strokewriting, it is important to discharge the solution in as slender astream as possible and in a stable and continuous state, without break,in order to form a thin film having a uniform thickness.

The maximum speed of discharging the resist solution is determined bythe water-head pressure in the discharge hole 130 a. To discharge theresist solution under a high pressure to attain the maximumsolution-discharging speed, the resist solution supplying section 142has a positive displacement pump, such as a cylinder pump, which forcesout the resist solution.

Further, the resist solution applied onto the wafer 1 spreads to someextent, depending on its viscosity. Thus, the pitch at which the nozzleunit 2 should be moved in the Y direction can be determined on the basisof the viscosity of the solution, and the solution application route isdetermined. Once the solution application route has been determined, therelative speed at which the nozzle unit 2 should be driven is determinedfrom the time of applying the resist solution (obtained from thesolution applying rate and the amount of solution to be discharged). Inthis apparatus, the relative drive speed of the nozzle unit 2 (e.g., 500mm/s to 1 m/s) is lower than the solution-discharging speed (e.g., 2m/s).

In the case where the nozzle unit 2 is driven while discharging theresist solution, the solvent may evaporate and the solution may be driedat its surface, possibly causing interruption of the solution stream. Toprevent this, the resist solution is discharged to the lower surface ofthe wafer 1. The solvent evaporates and rises upwards. In thisembodiment, the wafer 1 serves as a cover, inhibiting the evaporation ofprevented, whereby interruption of the solution stream can beeffectively avoided.

To prevent interruption of the resist solution stream effectively, theresist solution temperature control section 141 controls the temperatureof the resist solution. The resist solution temperature control section141 is a water jacket that contains temperature-adjusting water heatedto a prescribed temperature.

The system for supplying the solvent comprises a solvent pipe 143, asolvent valve 144 connected to the bypass passage 134, a solventtemperature control section 145, and a solvent supplying section 146.

The solvent valve 144 is a passage control valve. The valve 144 isclosed while the resist solution is being applied. It is opened onlywhile no resist solution is being applied, continuously passing thesolvent, which is controlled in temperature and concentration, throughthe discharge hole 130 a of the nozzle 130.

The solution supply valve 140, resist solution temperature controlsection 141, resist solution supplying section 142, solvent valve 144,solvent temperature control section 145 and solvent supplying section146 are connected to and controlled by a central control section.

The central control section 147 is the computer which controls allcomponents of this resist solution applying apparatus, not only thecomponents shown in FIG. 15 but also those not illustrated in FIG. 15.

A nozzle unit driver 149 for operating the nozzle unit drive mechanism117 which comprises the X-, Y- and Z-direction drive mechanisms and thelike, a sub-arm mechanism driver 150 for controlling the sub-armmechanism 112, and a reversing mechanism driver 151 for controlling thereversing mechanism 111 are connected to the central control section147.

The nozzle unit driver 149 operates in accordance with the solutionapplication route and the relative speed, both set by a route-speedsetting section 152 incorporated in the central control section 147. Theroute-speed setting section 152 has determined the solution applicationroute on the basis of the wafer size (the size of the circuit-formingregion 1 a), the basic pattern of solution application route, therequired amount of resist solution to apply, and the like, which arestored in an application condition file 148.

The wafer sizes available are 6 inches, 8 inches, 12 inches, and thelike. There are various basic patterns of solution application route,among which is a zigzag route (FIG. 12), a spiral route, and the like.The amount of resist solution to apply is determined from the desiredthickness of the film and the area to coat with the resist solution,because the use efficiency of resist solution is nearly 100% in thisapparatus. The relative speed, which is determined from the amount ofsolution to apply and the time of applying the solution, is veryimportant because it is greatly related with the thickness of the film.

The conditions of applying resist solution may be automatically set theconditions of applying the resist solution. Alternatively, an operatormay select desired conditions and input them into the route-speedsetting section 152.

The sub-arm mechanism driver 150 drives the sub-arm mechanism 112 in thedirection of the arrow shown in FIG. 14, closes the arms 120 to chuckthe wafer 1, and opens the arms 120 to unchuck the wafer 1.

As indicated above, the sub-arm mechanism 112 can hold the wafer 1,without touching the lower surface of the wafer 1. It receives the wafer1 at the reversing mechanism 111, transports the wafer 1 to a positionabove the resist solution applying mechanism 113, and holds the wafer 1at this position. When the wafer 1 is coated with the resist solution,sub-arm mechanism 112 takes the wafer 1 from the resist solutionapplying mechanism 113 and transfers the wafer 1 back to the reversingmechanism 111.

FIG. 16 is a schematic view showing an example of the reversingmechanism 111.

This reversing mechanism 111 has a wafer holding mechanism 153. Thewafer holding mechanism 153 has a Zθ drive mechanism 154 and waferholding arms 155 connected to the Zθ drive mechanism 154. Pins 156protrude upwards from the distal end of each wafer holding arm 155. Thepins 156 can touch the peripheral part of the wafer 1, i.e., the partoutside the circuit-forming region 1 a of the wafer 1.

Above the wafer holding mechanism 153, a reversing arm mechanism 158 isprovided for turning the wafer 1 upside down. The reversing armmechanism 158 is similar in structure to the sub-arm mechanism 112 (FIG.13B). It has arms 157 that can be opened and closed and holding pads 159that can hold the wafer 1 without touching the circuit-forming region 1a thereof.

The arms 157 are held by a drive unit 160 that is designed to drive thereversing arm mechanism 158. When driven by the drive unit 160, the arms157 turn the wafer 1 upside down, through 180°.

It will be described below how the reversing mechanism 111 operates, forexample, to transfer the wafer 1 from the main arm mechanism 110 to thesub-arm mechanism 112.

First, the main arm mechanism 110 holding the wafer 1 moves toward thewafer holding mechanism 153 of the reversing mechanism 111, thuspositioning the wafer 1 right above the wafer holding arms 155. Next,the wafer holding mechanism 153 moves the wafer holding arms 155upwards, whereby the wafer 1 is placed on the upper surfaces of the arms155.

Since the lower surface of the wafer 1 is not coated with resistsolution, the wafer 1 may be held at the central part of its lowersurface. Thus, the wafer 1 may be transferred from onto the waferholding arms 155 by being first held at its center part, then elevatedfrom the main arm mechanism 110, and finally lowered.

Next, the wafer holding arms 155 are moved up to the level where thearms 157 of the reversing arm mechanism 158. The arms 157 are closed,clamping the wafer 1 and the wafer holding arms 155 are moved downwards.Thus, the wafer 1 is transferred from the arms 157 of the reversing armmechanism 158.

Then, the drive unit 160 of the reversing arm mechanism 158 is operated,reversing the wafer 1 upside down.

After the wafer 1 has been reversed, the wafer holding arms 155 aremoved upwards again to take the wafer 1, thus reversed, from the waferholding mechanism 153. At this time, the pins 156, which protrude fromthe distal end of the arms 155 hold the wafer 1.

Further, the wafer holding arms 155 are lowered to the level where thesub-arm mechanism 112 is located. Before the wafer 1 is transferred tothe sub-arm mechanism 112, the Zθ drive mechanism 154 is operated,achieving the notch alignment of the wafer 1.

Upon completion of the notch alignment, the wafer 1 is transferred tothe sub-arm mechanism 112. The sub-arm mechanism 112 transports thewafer 1 to the resist solution applying mechanism 113 and positions thewafer 1 right above this mechanism 113.

Having the structure described above, the reversing arm mechanism 158can reverse the wafer 1, without touching the circuit-forming region 1 aof the wafer 1.

A mask member washing mechanism 114 is provided beside the resistsolution applying mechanism 113. The mechanism 114 will be describedbelow.

As shown in FIG. 1, the mask member 4 covers all upper surface of thewafer 1, except the circuit-forming region 1 a, thus preventing theperipheral part of the wafer 1 from being coated with the resistsolution. Hence, the mask member 4 is inevitably got dirty with theresist solution and should be regularly washed.

The mask member 4 dirty with the resist solution is removed from theresist solution applying mechanism 113 through an insertion/ejectionpath (not shown) and moved into mask member washing mechanism 114.

The mask member washing mechanism 114 holds a spare mask member 4′. Themask washing mechanism 114 receives the mask member 4 dirty with theresist solution, from the resist solution applying apparatus, andtransports the spare mask member 4′, washed clean, to the resistsolution applying apparatus. The mask member washing mechanism 114 thenwashes the mask member 4 got dirty.

The step of applying the resist solution, performed by the resistsolution applying apparatus, will be explained with reference to theflow chart of FIG. 17. The operations already detailed above will not bedescribed in detail.

(1) Loading of the Wafer (Steps S1 to S5)

At first, the wafer 1 is loaded from the main arm mechanism 110 into thereversing mechanism 111 (Step S1). Then, the reversing mechanism 111reverses the wafer 1 in the way described above (Step S2).

Next, the notch alignment of the wafer 1 is carried out before the wafer1 is transferred to the sub-arm mechanism 112 (Step S3). That is, alight-emitting section and a light-receiving sensor are arranged at theperiphery of the wafer 1, opposing each other. The Zθ drive mechanism154 rotates the wafer 1, and the wafer 1 is stopped upon rotatingthrough a particular angle when the notch 1 b (see FIG. 1) is detected.

When the notch alignment of the wafer 1 is completed, the wafer 1 istransferred to the sub-arm mechanism 112 (Step S4). The sub-armmechanism 112 transports the wafer 1 and holds it right above the maskmember 4 which has been set in the resist solution applying mechanism113.

(2) Actuation of the Nozzle Unit (Steps S6 to S9)

The nozzle unit 2 waits, set in the nozzle unit station 129 as shown inFIG. 4, until the wafer 1 is positioned in the resist solution applyingmechanism 113 (Step S6).

At this time, the solution supply valve 140 and the solvent valve 144are closed and opened, respectively, as mentioned above. The solventtherefore continuously passes through the small discharge hole 130 amade in the nozzle 130, thus preventing the clogging and drying.

When preparation for the application of resist solution to the wafer 1is completed, the nozzle unit 2 is actuated. More precisely, the solventvalve 144 is closed, stopping the discharging of solvent (Step S7). Thesolution supply valve 140 is opened, supplying the resist solution intothe discharge hole 130 a (Step S8). As the resist solution is suppliedinto the discharge hole 130 a, the solution supply valve 140 is closed,and the nozzle 2 is moved from its waiting position to a position in thesolution applying mechanism 113 (where the nozzle 2 oppose the pointSTART shown in FIG. 1) (Step S9).

While the wafer 1 and the nozzle unit 2 are being loaded, the solventatmosphere is continuously controlled in the solution applying mechanism113. That is, the solvent in the solvent channel 122 of the solutionapplying mechanism 113 is kept controlled in temperature and surfacelevel. The solvent atmosphere is controlled by an atmosphere controllingsection 161 provided in the central control section 147.

(3) Application of the Resist Solution (Step S10)

When the wafer 1 is positioned in the solution applying mechanism 113,the central control section 147 moves the nozzle unit 2 and wafer 1,relative to each other, in accordance with the solution applicationroute and relative speed set by a route-speed setting section 152 andalso with other conditions. The resist solution is thereby applied tothe wafer 1.

In the present embodiment, the nozzle unit 2 is driven back and forth inthe X direction from the point START shown in FIG. 12, while beingintermittently moved at turning points in the Y direction at a certainpitch. The wafer 1 is thereby coated with the resist solution.

To move the nozzle unit 2 along the route shown in FIG. 12, it isnecessary to decelerate and accelerate the nozzle unit 2 at each turningpoint in the X direction. This may result in variation in the thicknessof resist solution film. In order to avoid such variation, the nozzleunit 2 is turned back above the mask member, that is, outside thecircuit-forming region 1 a of the wafer 1. Thus, the nozzle unit 2 ismoved at a constant speed over the entire the circuit-forming region 1a.

The film of the resist solution applied onto the wafer 1 is therebyadjusted in accordance with the diameter of the solution stream, therelative speed of the nozzle unit 2 and the spread of the resistsolution on the wafer 1. As a result, a solution film having a uniformthickness is formed on the circuit-forming region 1 a of the wafer 1.

In this embodiment, too, the evaporation of solvent is prevented bycontrolling the air flow during the application of resist solution andthe agitation of the film of resist solution applied is performed, inthe same way as in the first embodiment.

(4) Unloading of the Wafer (Steps S11 to S13)

When the application of resist solution is completed, the sub-armmechanism 112 is moved back from the solution applying mechanism 113 andtransported to the reversing mechanism 111. Then, the wafer 1 is turnedupside down, in the direction reverse to the direction in which it hasbeen turned to be loaded. The wafer 1, thus turned, is transferred tothe main arm mechanism 110 (Steps S12 and S13).

The main arm mechanism 110 thereafter transports the wafer 1 to theplace where the next step (baking) is carried out, and loads the nextwafer 1 into the reversing mechanism 111 (Step S1 et. seq.)

(5) Holding of Nozzle at Nozzle Unit Station (Step S14)

Until the main arm mechanism 110 loads the next wafer 1, the nozzle unit2 is held at the in the nozzle unit station 129 (Step S14). At thistime, the solvent valve 144 is opened, thereby passing the solventthrough the discharge hole 130 a. This prevents the hole 130 a frombeing clogged.

The structure described above can attain not only the advantages of thefirst embodiment but also the following advantages.

First, interruption of the resist solution stream can be reliablyprevented, to form a thin film of solution that has a uniform thickness.

That is, when the resist solution in a manner of single-stroke writing,it necessary to apply the solution in as slender a stream as possibleand to prevent interruption of the solution stream in order to form athing film of solution that has a uniform thickness. The solution streammay probably be interrupted if the viscosity of the resist solutionchanges during the application of the solution. Further, there is highpossibility that the resist solution nozzle is clogged, and it is alsonecessary to prevent such clogging.

In the present invention, the wafer 1 is turned upside down, and theresist solution is discharged upwards from the nozzle unit 2, coatingthe wafer 1 with the solution. Thus, the solvent atmosphere in the spaceright below the wafer 1 can be easily maintained appropriately. Thesolution stream can therefore be always maintained at a constantviscosity, however slender the solution stream is. This preventsinterruption of the stream of the resist solution.

That is, the solvent contained in the resist solution evaporates andflows upwards. In the ordinary coating method, the solvent easilyevaporates because from the resist solution because the resist solutionis applied to the upper surface of a wafer. It is therefore requiredthat a special structure be employed to maintain the solvent atmospherewith high precision when the solution is applied in a manner ofsingle-stroke writing as in the present invention.

By contrast, in the present invention, a solution-applying space isprovided at the lower surface of the wafer 1, whereby the wafer 1 servesas a cover. Thus, an appropriate solvent atmosphere can be maintainedand can prevent interruption of the stream of resist solution, withoutthe necessity of employing a complex structure.

If the case of applying the resist solution in this manner, the spreadof resist solution is more inhibited after the resist solution has beenapplied, than in the case where the resist solution is applied to theupper surface of the wafer. Hence, the solvent is effectively preventedfrom evaporating from the resist solution applied to the wafer.

As a result, the change in the viscosity of resist solution, whichoccurs at about the start and end of applying the solution can bereduced to a minimum. This can contribute to the enhancement ofresolution.

Second, air can be easily expelled from the nozzle unit.

Namely, since the discharge hole 130 a of the nozzle 130 opens upwardlyin the structure according to this invention, air can be automaticallyexpelled when the nozzle is replaced with another. Neither a specificstep nor a special structure is required to expel air from the nozzle.

The second embodiment is not limited to the structure described above.

First, the mechanism for preventing the clogging in the discharge holeof the nozzle unit is not limited to the one shown in FIG. 3. Any otherstructure may be utilized.

For example, a cover for covering the distal end of the nozzle unit maybe provided, in addition to the nozzle unit station.

Second, the solution application route is not limited to the one that isillustrated in FIG. 12. Rather, it may be spiral as in the firstembodiment or may be of any other type. In order to form a film ofresist solution that has a uniform thickness, the resist solution may beapplied twice, first in one direction and then in another.

Third, the solution used to form a film is resist solution in theapparatus of this embodiment, as in the first embodiment. Nonetheless,the solution is not limited to resist solution. Any other solution maybe applied, instead. Examples of other solutions are a solution forforming an interlayer insulating film, a solution for forming a highlyconductive film, a ferroelectric solution, sliver paste, and the like.Further, the substrate to be processed is not limited to a semiconductorwafer 1; instead, it may be an LCD substrate or an exposure mask.

Fourth, a mask member 4 is provided in the first embodiment.Nevertheless, this member need not be provided. If this is the case, itsuffices to provide a mechanism for discharging residual resistsolution, such as a cup, below the wafer 1, to receive the residualresist solution.

Moreover, the mask member may be of any one of the types shown in FIGS.11A to 11D. If so, the apparatus can be made smaller.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A method of forming a coating film on asubstrate, comprising: holding the substrate by a substrate holder in aprocess space, the substrate holder holding the substrate to directupward a surface to be provided with the coating film; supplying acoating solution for forming the coating film onto the surface of thesubstrate from a nozzle unit while moving the substrate holder and thenozzle unit relative to each other, the coating solution beingcontinuously discharged as a stream from a discharge hole of the nozzleunit; and maintaining a solvent atmosphere of a predeterminedconcentration in the process space by an atmosphere control mechanism,the atmosphere control mechanism being configured to control atemperature and a surface level of a solvent and including a solventchannel positioned to store the solvent, a top plate member defining aceiling of the process space and having an insertion section in whichthe nozzle unit is inserted, and a heater disposed on the top platemember to heat the process space and the nozzle unit.
 2. The methodaccording to claim 1, comprising discharging the solvent around thecoating solution from the nozzle unit, when supplying the coatingsolution.
 3. The method according to claim 1, further comprisingcovering a periphery of the substrate by a mask member.
 4. The methodaccording to claim 1, further comprising controlling an airflow over thesurface of the substrate such that the airflow is directed toward aregion of the substrate on which the coating solution has already beenapplied.
 5. The method according to claim 1, further comprisingvibrating the substrate to render flat a surface of a film of thecoating solution applied on the substrate.
 6. The method according toclaim 1, comprising scanning the substrate substantially entirely withthe nozzle unit while reciprocating the nozzle unit, when supplying thecoating solution.
 7. The method according to claim 1, wherein thecoating solution is a resist solution.
 8. A method of forming a coatingfilm on a substrate, comprising: holding the substrate by a substrateholder in a process space, the substrate holder holding the substrate todirect upward a surface to be provided with the coating film; coveringthe substrate by a mask member other than a target region to be providedwith the coating film; driving a plurality of receiving members placedabove the mask member for receiving the coating solution, to control adistance between the receiving members in accordance with a width of thetarget region; and supplying a coating solution for forming the coatingfilm onto the surface of the substrate from a nozzle unit while movingthe substrate holder and the nozzle unit relative to each other, thecoating solution being continuously discharged as a stream from adischarge hole nozzle unit.
 9. The method according to claim 8, whereinthe mask member comprises a plate having an opening corresponding to thetarget region.
 10. The method according to claim 8, further comprisingsetting a speed at which the nozzle unit and the substrate are movedrelative to each other, and a route along which the coating solution isto be applied, such that the nozzle unit and the substrate aredecelerated, turned, and accelerated over the mask member and moved at aconstant relative speed over the target region.
 11. The method accordingto claim 8, comprising scanning the substrate substantially entirelywith the nozzle unit while reciprocating the nozzle unit, when supplyingthe coating solution.
 12. The method according to claim 8, wherein thecoating solution is a resist solution.